This invention relates to sensor devices and more particularly to sensor devices for sensing fluid pressure.
More particularly, this invention relates to fluid pressure sensor devices capable of providing an indication when the fluid pressure within a container exceeds an established level.
Sensor devices having the ability to provide the above described capabilities are well known in the art. Particularly well known are those for detecting and indicating pressure differentials in closed systems. To date, a large majority of this variety of sensing devices have required either a spring-biased or magnetically actuated motion, or most likely a combination of the two. Two examples of such devices are illustrated in U.S. Pat. Nos. 3,499,415 and 3,502,048. In these and similar devices, usually the magnetic or spring forces are overcome during a gain or loss in pressure, the result being either an indication or a corrective measure undertaken. Still another example of this type of sensor is illustrated in U.S. Pat. No. 3,364,897. This sensor requires a pair of spring members in addition to a pair of magnetic devices positioned respectively within each spring.
As can be appreciated, sensors of the above described variety possess at least two distinctive operating deficiencies. Those utilizing magnets or similar members are capable of efficient operation only as long as these members maintain their magnetic properties. Thus, after prolonged periods of operation, these sensors have proven unsatisfactory. Sensors employing springs to bias moving components are usually operable only within definitely limited temperature ranges due to the effect of extremely high or low temperatures on the expansion properties of the spring. Furthermore, as in U.S. Pat. Nos. 3,364,897 and 3,499,415, the springs are exposed to the fluids being measured, thus providing an opportunity for contaminate or similar adverse buildup on these members if required to detect fluids having such undesirable properties.
It is believed, therefore, that a sensor device capable of providing an indication of excessive fluid pressure in a container without requiring utilization of magnetic or spring-biased motion will constitute an advancement in the art.